Many chemical processes involve feeding an organic liquid stream to a chemical reactor. Raw feed materials may have to be purified to remove various impurities such as water and molecular oxygen before being fed to the chemical reactor.
For example, benzene is a basic industrial chemical used as a feed material in processes for making many other basic chemicals, such as phenol, cyclohexanone, cyclohexane, cyclohexene, cyclohexanol, xylene, and cumene. Two common impurities are water and molecular oxygen, which can enter the benzene feed during storage and transportation on exposure to the storage tanks and ambient air. Under extreme conditions, the benzene feed may become saturated by water and oxygen after long exposure to the ambient. In many of these processes, a catalyst sensitive to impurities in the benzene feed is used, and the presence of water and oxygen at high concentrations can lead to undesirable side reactions producing byproducts, which can poison the catalyst as well. To achieve and maintain high performance of the catalyst in many of these processes, it is highly desirable to reduce the water and/or oxygen concentrations in the benzene feed to acceptable levels.
Particularly, in the process for making cumene from benzene via propylene alkylation, a solid acid alkylation catalyst is typically used. The solid acid can be an aluminosilicate molecular sieve such as a zeolite of the MWW frame work, which is sensitive to water and oxygen. Moreover, oxygen and water can react with propylene, resulting in byproducts that can reduce catalyst performance. Likewise, in the process for making cyclohexylbenzene from benzene via hydroalkylation, a bi-functional catalyst comprising a hydrogenation metal component such as Pd and a solid acid component such as an aluminosilicate molecular sieve (e.g., a zeolite of the MWW frame work) may be used. Water and oxygen content in the benzene feed used in this process is desirably low as well.
Existing processes for removing water and oxygen from crude organic liquid streams such as crude benzene streams suffer from one or more of the drawbacks of high energy consumption, high material and equipment costs, and high benzene feed temperature at high concentration of molecular oxygen leading to oxidation of benzene by the dissolved oxygen.